Ink jet printers generally have a ‘jet stack,’ a stack of brazed steel plates that have manifolds to route the ink from ink reservoirs to an array of jets from which ink is dispensed. The jet stack may consist of several plates and the plates need to align correctly for proper functioning of the ink jet printer.
Current implementations of jet stack plates use a single hole on each plate, with each successive plate from an aperture plate to the diaphragm plate having a hole of a larger diameter. The diaphragm plate resides the closest to the jet, generally a transducer receives a signal to activate, as it activates it depresses the diaphragm and pushes a droplet of ink through a jet. Ideally, as the plates are stacked together, the holes would be perfectly concentric, but variation almost always occurs.
The variation is measured with an automated video system. Poor contrast between the hole edge and the plate to which the current plate is bonded from below results in erroneous measurements. The plates are shiny, stainless steel and the hole and surface quality vary. The automated video system uses top lighting and it becomes difficult for the system to sort out reflections and locate the hole edges to determine if the holes align correctly. Erroneous measurements then occur.
If caught, the erroneous measurements require re-measuring manually, which consumes time and resources. If they erroneous measurements are not caught, the jet stack plates do not align correctly. The jet stack will still operate but at a lower efficiency. Further, the management of the process flow is affected, because the error in the process is not corrected. In some instances, the re-measuring and manual alignment process is skipped entirely, being deemed as too high a cost for the results.